CP 950 Power Off

[Martin McCaffery]

We recently installed a CP 950, replacing our very old 650. I didn't notice when it was installed that the installer plugged it into the rack, and not the UPS. The other day I plugged it into the UPS. So now when we shut down the rack at night, the 950 stays on.
Is there an off button or an off command that can be sent to the 950 so it closes down? Or are they trying to force us into leaving it running 24/7?

[Jim Cassedy]

I don't know the official recommendation. The only CP-950's I've worked with were at Dolby's
screening room- - and they were left on 24/7. But if it failed there were two more just sitting
in the rack- - and a warehouse full of them a couple of blocks away.

[Steve Guttag]

There are no power buttons or shutdown commands for the CP950. Truth be told, the CP650 didn't have a power button either. The big white thing that looked like a power button was really a "bypass" button. Did you ever notice that the projector LEDs remained lit and optical sound would still pass when "off." The CP750 didn't have a power button and...really, you'd have to go back to the CP200 to find the last Dolby processor that had a, kill all power, button/switch to the sound processor.

Traditionally, people used the circuit breakers to the sound rack to kill sound power.

[Rick Cohen]

We have each auditorium sound system on it's own power conditioner/distribution outlet array which has it's own master on/off switch, and is powered by the UPS.

[Leo Enticknap]

As others have noted, the CP950 does not have a soft power off/standby (or "eco mode" in Barcoese) function. If you want software and/or remote control of the power on/off, a cheap and effective way would be to power it through a Wattbox. This allows you to turn the power on and off via a web UI, an API command (e.g. in an automation cue from your server), or on an automatic schedule.

[Marcel Birgelen]

For the CP850 with redundant power supplies you even need two programmable outlets to shut it down.

I'm not sure what the official policy with the CP950 is, but the CP850 being essentially a server running Linux, much like those first generation cinema servers, the default policy is that you just leave it running all the time, sucking up dust and burning power...

[Frank Cox]

Crash-stopping a Linux computer is generally a bad idea as well.

Which means that a well-designed unit should always have a shutdown button or procedure.

[Harold Hallikainen]

I wonder if one could write a simple script to shut down the server upon receiving a command through UDP or TCP using inetd ( https://en.wikipedia.org/wiki/Inetd ). I'm using inetd to receive UDP packets on an Alma Linux server. Of course, once the server is shut down, you need a way to get it back. Perhaps power cycling would start it up again.

[Steve Guttag]

On our systems with "modern" servers (IMS3000, SR-1000), I have the user (or QSYS) tell the automation (Eprad eCNA) to shut down the screen/complex. The eCNA will issue a command to the server and wait for it to shut down. Once that is done, it will kill power to the projector too. As for sound, those soundracks that are under eCNA control, they too will be told to power down (via contactor). Those rooms with QSYS will just have the amps go into Standby but the Cores remain on 24/7 (as do the peripherals, though they could be fully powered down too).

The reverse happens at the beginning of the day...the eCNA powers up the projector, which will power the server.

A down-side to the proper shutdown is the one that immediately jumps from power down to power on thinking that once the a server is told to shutdown that they can, in short order power it back up...nope, once you shut down, you need to commit to your decision, though we do have an immediate off overide...that is not encouraged as it could cause corruption to the server. Interestingly, Barco has made their server more robust in that there is no off/shutdown for the ICMP-X...just turn the projector off (or put it into ECO mode, on an S4).

[Frank Cox]

Many computers have a bios setting for what to do when power is restored. The options usually are power on, power off or restore to what it was when the power went off.

[Steve Guttag]

Most IMB/IMS type servers and all cinema processors don't tend to allow one into the BIOS sort of thing. But yes, most BIOS give one the option of what to do on power up. Most default to Power OFF. A warning sign of a flat battery is the server no longer just boots up on its own (and it complains about what day it is).

[Frank Cox]

So it's down to sloppy design work.

[Martin McCaffery]

Seems the simple answer is to get Dolby to put a shutdown function in a future software update. If dealing with Dolby in that context can be considered simple.
Thanks for all of the info.

[Steve Guttag]

I guess you are entitled to your opinion, Frank. But, before I'd pass judgement, why not talk to the engineer(s) that made the decision and then decide if their reasoning was sound. The life span of most Dolby processors exceeds most computers. They are designed for the environment for which they are to be used. They are not designed for every environment (or they'd still have a multichannel analog input) too.

[Frank Cox]

Pulling the power plug on a Linux computer (or any computer, for that matter) is a bad thing:

1. Data Loss: Pulling the power plug abruptly interrupts all processes and operations on the system. If files were being written or modified at the time, it can lead to data corruption or loss.
2. File System Corruption: Abruptly cutting power to a computer can lead to file system corruption. The file system may not have had a chance to properly finalize any ongoing operations, leaving it in an inconsistent state that could cause errors or prevent the system from booting properly.
3. Hardware Damage: Sudden power loss can potentially damage hardware components, particularly storage devices like hard drives or solid-state drives (SSDs). These components may be in the middle of read or write operations when the power is cut, leading to physical damage or data corruption.
4. Operating System Integrity: Pulling the power plug can also lead to problems with the operating system itself. Critical system files may be left in an inconsistent state, leading to boot failures or other issues when the system is restarted.
5. Potential Data Corruption: In addition to data loss, pulling the plug can also cause corruption in system files or configuration settings, which can impact the overall stability and performance of the system.

If the engineer(s) who made that decision to not include a proper shutdown procedure on this machine aren't aware of these things, they should probably be working for Boeing.

If they were aware of these things and went ahead anyway, that's arguably even worse.

If the Dolby folks are reading this they are more than welcome to chime in with their reasoning. I would be very surprised if it's anything more than "save fifty cents on a switch and two bucks on a soldering job".